Understanding life-space characteristics based on smart-phone collected data Project Summary Smart-phone is a promising device for collecting data of individuals' physical activity, travel mode, and life-space. In collaboration with experts n geriatrics and spatial epidemiology, this proposal translates and enhances traditional life-space measures into smart-phone based ones. Using geographic information system (GIS), signal processing, and spatial statistical methods, this proposal aims to develop a set of methods for processing smart-phone collected data to generate life-space information that is suitable for clinical intervention. Specifically, it estimates the location, duration, and physical intensity information of activities from the phone collected GPS and accelerometer data. Such information is then integrated to generate new life-space measures. The proposed life-space measures will be calibrated and validated using data collected by volunteers and compiled by GIS. In summary, this study will significantly enhance our understanding of life-space characteristics collected by smart-phone. The template of smart- phone data processing will not only directly benefit clinical intervention of geriatric patients, but will also facilitate the understanding of patients' spatial behaviors in various health conditions.